AB0214 SERUM IMMUNOGLOBULINS LEVEL IN A COHORT OF RHEUMATOID ARTHRITIS PATIENTS ON DIFFERENT TREATMENT OPTIONS
Authors: C. Mogosan, E. M. Marin, C. Popescu, L. Enache, B. Dumitrescu, M. Agache, O. G. Dinache, C. E. Ionescu, D. Minca, C. Codreanu
Journal: Annals of the Rheumatic Diseases (2022)

Background Serum immunoglobulins (Ig) A, G, and M (IgA, IgG, and IgM) are not routinely evaluated in rheumatoid arthritis (RA). There are some reports that rituximab (RTX) may induce hypogammaglobulinemia (1). Under normal conditions, IgM provides a rapid immune response and is involved in tissue homeostasis, whereas IgG and IgA are long-lasting high-affinity antibodies, the latter mainly providing mucosal immunity (2). Objectives The evaluate serum Ig levels (IgG, IgM, IgA) in a cohort of RA patients and potential therapeutic influences. Methods We performed a retrospective study in a cohort of 104 patients with RA exposed to different therapeutic agents, without switch for at least 1 year (conventional synthetic disease modifying drugs - csDMARDs, biologics and JAK inhibitors - JAKi); the collected data included demography, disease characteristics, treatment exposure (molecules, treatment line), serum level of IgA, IgG, IgM. Results 104 patients, mean age 60.3 years (±11.9), with a disease duration of 15years (±9.8), 83.7% women; the mean exposure to the current treatment option (without switch) was 3.7 years (±3.8); 20.2% (21 pts) were on csDMARDs, 70.2% (73pts) on biologics and 9.6% (10pts) on JAKi. 90.4% (83pts) used combination therapy along with biologics and JAKi. The biologics used were: 58.9% RTX, 31.5% TNFinhibitors, 8.2% IL-6 blockers and 1.3% abatacept. At cohort level, we found hypogammaglobulinemia in 12.5% for IgG, 9.6% for IgM and 7.7% for IgA, independent of the treatment duration. Low IgG levels were related mostly to RTX exposure (53.8%) followed by TNFi (23.1%) and with equal values anti-IL-6, JAKi and csDMARDs (7.7%). Low IgA levels were noted almost in RTX exposure (75%), followed by TNFi and anti-IL-6 (12.5%, each). Low IgM levels appeared in RTX group (90%) and csDMARDs (10%). No relations between Ig levels and the treatment option (the line of intervention). The Ig mean values were significantly different across treatment groups; for IgG: 9.55g/L in RTX vs 11.68 g/L in TNF inhibitors (p&lt;0.05) and 12.64 g/L in csDMARDs (p&lt;0.05); for IgA: 2.17 g/L in RTX vs 3.35 in JAKi (p&lt;0.05); for IgM: 0.84 g/L in RTX vs 1.82g/L in TNF inhibitors (p&lt;0.001) and 1.58 g/L in JAKi (p&lt;0.05); also IgM were significantly lower in csDMARD group (1.22g/L compared to TNF inhibitors values (1.82g/L), (p&lt;0.05). The serum levels of IgG and IgM (not IgA) were negatively associated with disease duration r = -0.22, p&lt;0.05 and r = -0.2, p&lt;0.05) and age (r =-0.3, r=-0.26, p&lt;0.01). No impact of disease activity, nor patient gender or seropositivity of rheumatoid factor or ACPA. Conclusion Low serum levels of IgG, IgM and IgA are seen mostly with RTX exposure, but appear with other treatment exposures as well, which may influence the rate of future infections. Even if our study lacks assessment of baseline Ig levels, it is clear that treatment option has an influence on Ig levels. Future studies are needed to clarify all contributors to these results. References [1]Marco, H., Smith, R.M., Jones, R.B. et al. The effect of rituximab therapy on immunoglobulin levels in patients with multisystem autoimmune disease. BMC Musculoskelet Disord 15, 178 (2014). https://doi.org/10.1186/1471-2474-15-178 [2]Hoffman W, Lakkis FG, Chalasani G, Cells B. Antibodies, and More. Clin J Am Soc Nephrol (2016) 11:137–54. doi: 10.2215/CJN.09430915 Disclosure of Interests Corina Mogosan Speakers bureau: Novartis, Lilly, Pfizer, EwoPharma, Abbvie, Sandoz, Eliza Mihaela Marin: None declared, Claudiu Popescu Speakers bureau: Abbvie, Luminita Enache Speakers bureau: Abbvie, Bianca Dumitrescu Speakers bureau: Abbvie, Pfizer, Lilly, Mihaela Agache: None declared, OANA GEORGIANA DINACHE: None declared, Catalina Elena Ionescu: None declared, Dragos Minca: None declared, Catalin Codreanu Speakers bureau: Abbvie, Pfizer, Novartis, Lilly, EwoPharma